Ischys · ΙΣΧΥΣ

A private, on-device workout tracker. Ischys (ἰσχύς) is Ancient Greek for strength. Your entire training log lives on your phone — no account, no server, no cloud. Nothing ever leaves the device.

The design is a precision instrument: monochrome, near-black, sharp, and legible mid-set with sweaty hands. Big number targets, previous-session references one tap away, and the accent colour reserved for a single action — completing a set.

---

What it is

• 100% on-device. Install and start tracking immediately. No sign-up, no backend to run. The app is a self-contained React Native / Expo app with a local SQLite database and all the training logic (volume, estimated 1RM, PR detection, streaks, charts) running in TypeScript on the phone.
• Private by construction. Because there is no server, your data can't be collected, sold, or breached. It backs up with your normal device backup (iCloud), and you can export a JSON/CSV copy anytime.
• Yours to build. MIT-licensed. Clone it, build it, run it, change it.

Features

• Log workouts (weight × reps), warmup / drop / failure set types, rest timer.
• Routines — build them, start a session that prefills from your last session (progressive overload), save a finished workout as a routine.
• Personal records (best set, est. 1RM, best volume, max reps) detected on finish, with per-exercise history and charts.
• Profile stats — workouts, volume lifted, weekly training bars, streaks.
• Apple Watch companion (mirror + control a live workout), Live Activity on the Lock Screen, and Apple Health (heart-rate read, workout write).
• Export / import — a JSON or Hevy-compatible CSV, for backup or moving in from another tracker.
• 736-exercise catalog bundled in the app (from free-exercise-db, public domain).

Platform support

iOS only, for now. Ischys is built and tested on iPhone (iOS 26, Expo SDK 57), and its headline features — Live Activity, the Apple Watch companion, and Apple Health — are iOS-specific with no Android equivalents yet. It's a React Native / Expo app, so an Android build is possible in principle, but it has never been built or run on Android and is entirely untested there. Treat Android as unsupported until someone does that work — contributions welcome.

Stack

React Native + Expo SDK 57 (New Architecture), expo-sqlite + Drizzle ORM for the on-device database, TypeScript throughout. Native modules for the Watch companion, Live Activity, and HealthKit live under frontend/modules/ and frontend/targets/.

Ischys/
└── frontend/
    ├── app/            screens (expo-router)
    ├── src/
    │   ├── db/         SQLite schema, migrations, bundled catalog seed
    │   ├── data/       local repository (the app's data layer)
    │   ├── domain/     pure training logic (stats, records, streaks…) + tests
    │   └── components/ UI
    ├── modules/        local native modules (Live Activity, HealthKit)
    └── targets/        Apple Watch app + Live Activity widget

Build & run

Ischys isn't on the App Store yet, so building from source is the only way to run it today. You'll need macOS with Xcode (for the iOS build) and a free Apple developer account to sign it onto your own device.

cd frontend
npm install
npx expo run:ios --device   # build + install on a connected iPhone
# or drop --device to run in the iOS Simulator

The app opens straight to your training — there's no server to point at and no sign-in. npm run typecheck and npm test (pure-logic unit tests, run in both UTC and a non-UTC timezone) gate every change.

Licence

MIT — see LICENSE. Third-party attributions in NOTICE.